1. FIELD OF THE INVENTION
The present invention relates to surgical instruments, and, more particularly, to trocars which are used to pierce or puncture an anatomical cavity to provide communication with the inside of the cavity during a surgical procedure.
2. DESCRIPTION OF THE PRIOR ART
Endoscopic surgery, and in particular laparoscopic surgery, constitutes a significant method for performing surgeries and has become the surgical procedure of choice, because of its patient care advantages over "open surgery." In particular, a significant advantage of laparoscopic surgery over open surgery is the decreased post-operative recovery time. In most instances, a patient is able to leave the hospital within hours after laparoscopic surgery has been performed, as compared to the multi-day hospitalization necessary to recover from open surgical procedures. Further, laparoscopic surgery provides decreased incidents of post-operative abdominal adhesions and decreased post-operative pain. Cosmetic results are also enhanced with laparoscopic surgery.
A trocar is an essential medical instrument for use in laparoscopic surgery, because it is used to puncture the wall of an anatomical cavity. A trocar includes a tube or cannula and a sharp, generally pointed cutting element called an obturator. The obturator fits within the cannula and has a sharp piercing tip at its end.
Conventionally, a laparoscopic trocar insertion procedure is preceded by the insufflation of the abdominal cavity with carbon dioxide. The introduction of this gas into the abdominal cavity lifts the abdominal wall away from the internal viscera. The abdominal wall is then penetrated with the trocar, and after insertion of the trocar through the abdominal wall, the obturator is removed by the surgeon, leaving the cannula or tube protruding through the body wall. Laparoscopic instruments can then be inserted through the cannula to view internal organs or to perform surgical procedures.
Penetrating the wall of the abdominal cavity with the trocar is done relatively quickly, and while the obturator encounters a fair amount of resistance from the skin muscle and tissue membranes of the abdominal wall, the resistance to the trocar drops quickly once the cutting element passes through the abdominal wall. Within the abdominal cavity, the sharp point of the cutting element may easily injure or cut an internal organ upon the slightest of contacts. Accordingly, many trocars include a safety shield that snaps forward to cover the sharp point of the obturator, once the trocar has penetrated the abdominal wall. Preferably, the safety shield is locked into place once the abdominal wall has been penetrated, and cannot be unlocked absent positive intervention by the surgeon.
While locking safety shields for trocars have been available, the locking mechanisms employed in these trocars has suffered from the disability that consistent pressure is not placed on the safety shield. Further, the architecture of locking mechanisms in the prior art trocars has not been open, which has made those trocars difficult to sterilize.
Despite the fact that trocars are hand-held instruments, prior art trocars have been less than ergonomically friendly to the user. Rather, prior art trocars have suffered from the disability of being difficult to control, since they are not designed to provide for a plurality of hand positions or for different holding levels that allow for different size hands to manipulate the trocar.
The foregoing and other shortcomings of prior art trocars have been overcome by the trocar of the present invention.